Dates - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 184

solution and date fibers is filtered to separate the solid ma-
terials and to obtain a clear solution. To prevent the growth
of different fungus materials, some fungicide is added to
the solution (Mustafa et al., 1983b). The obtained dilute
solution has 12 ◦ -15 ◦ Brix. This solution heated under vac-
uum can be concentrated to 70 ◦ Brix, which is a very good
concentration for long shelf life. The evaporation is usually
carried out at 55 ◦ -60 ◦ C to prevent burning of sugars. The
optimum conditions for obtaining the maximum extraction
for water-date system are: (1) a temperature of about 70 ◦ C;
(2) water-to-dates weight ratio of 3:1, after which the re-
quired energy for evaporation could compensate for the
additional extraction of sugars; and (3) a contact time dura-
tion of about 30 min, after which the amount of extraction
is negligible. From each kilogram of dates about 600 g of
70 ◦ Brix date syrup is obtained. The efficiency of extraction
of sugars from dates is a very important factor (Mowla and
Mowla, 2007).

malic) and pectic enzymes for clarification of date fruit
extract. They found that type of acid used for initial pH
adjustment had a significant effect on the color and clarity.

Use of dates in bread making
Al-Saidy and Al-Dujaili (1979) reported the use of date
syrups as a substitute for table sugar in bread making. They
found that more than 3% of the crystal sugar could be re-
placed by date syrup, without affecting the bread character-
istics. Al-Zubaydi et al. (1983) studied the effect of various
date syrups on experimental breads with the straight dough
procedure. They reported that date syrups were found to
cause a substantial increase in the weight and volume of
loaves and also improved the texture of the finished bread.
Date syrup treatment improved all characteristics except
crumb color, which was adversely affected by date syrups.
Aleid (1998) reported the incorporation of date syrup into
bread dough formula as a sugar substitute at 0%, 3%, 6%,
9%, and 12% using flour of 75%, 85%, and 95% extrac-
tions. The baked loaves were tested for internal and external
characteristics and loaf volume. Breads with 6% and 9%
date syrup, at 85% and 95% extraction, exhibited a high
total bread score compared with no sugar or 4% sucrose
treatments. Loaves with date syrups had slightly higher
volume than those with or without sucrose. Date syrup had
no effect on crumb lightness. The replacement of sugar with
date syrup up to 6% is strongly recommended.

Date syrup extraction by hydraulic pressure
Date syrup could be produced as an incidental by-product
when bagged humid dates are heaped for several months
and the syrup oozes out by the force of their weight (FAO,
1996). Aleid et al. (2007) utilized second-grade date variety,
'Ruzeiz,' to extract date syrup by means of high hydraulic
pressure under room temperature. The sugar content was
70-85% on dry weight bases, most of them being reducing
sugars. This process gave a yield of 40-50%. The color of
syrup was light brown compared with the syrup obtained
from the heat extraction experiment (85 ◦ -95 ◦ C) which was
dark brown and with a caramelized flavor. However, the
extraction time in the heat extraction process was relatively
short, giving high yield compared to the cold extraction
process (Aleid et al., 2007).

MANAGING QUALITY IN DATE
PROCESSING
Making dates safe involves the suppliers, the processors,
and distributors. Date products should have a marketable
quality and also have to be safe for consumers. Even at
the smallest scale of production, main risks are contami-
nation by microorganisms, toxins, chemical contaminants,
foreign matter and excess of moisture content, degrada-
tion of the nutritional value, or pest infestations. Most of
these risks can be easily prevented or mitigated by a better
knowledge of the risk factors for dates, by safe handling,
a careful inspection, and possibly analysis—in short by a
better management of such commodity.

Clarification of date extract
Pectins (2-6% in different varieties) are the most important
agent of turbidity in date extract. Pectinases (a mixture
of pectin esterase, polygalacturonase and pectinlyase) are
usually are added to convert pectins in solvent compounds
(Alkovarta et al., 1998; Kashyap et al., 2001).
An efficient clarification of date syrup has been achieved
by the use of calcium phosphate precipitation. Ehrenberg
(1977) reported that treating the date extract with lime
followed by purification with cation and anion exchang-
ers' yielded syrup with a purity of 99.26%. Nakahara and
Tetsujiro (1977) reported the use of an ultrafiltration mem-
brane with 20,000 molecular weight to obtain a clear date
syrup which can be used as a flavoring agent for processed
foods. Niazmand et al. (2007) used two acids (formic and

GMP in date processing
GMP refers to the minimum sanitary and processing con-
ditions required in a properly built processing plant. Dates
must be held under conditions that prevent contamination
and the growth of undesirable insects and microorganisms.
Processing and packaging steps, such as fumigation, sort-
ing, cleaning, drying, packaging, and so on, must be per-
formed in a manner that: provides adequate protection from